The present invention is directed to devices for improving the efficiency of fuel and has particular application for improving the efficiency of fuel used in vehicles. Various arrangements exist which deal with this problem. For example, U.S. Pat. No. 3,349,354 discloses a magnetic device which treats hydrocarbon fuel by flowing the fuel through the hollow center of a magnet assembly and thence into a chamber having means for applying an electromagnetic force so that the fuel is subjected to the combined effects of a very strong magnetic flux and to the influence of an electric field.